macOS

support nested VM barrier synchronization #870

Job	Run time
make (check, macos-14)	1h 3m 48s
make (check, macos-14, --with-gcc=gcc-14)	1h 6m 2s
make (check, macos-14, --with-jemalloc --with-opt-dir=$(brew --prefix jemalloc))	42m 12s
make (test-bundler-parallel, macos-14)	1h 2m 54s
make (test-all, --repeat-count=2, macos-14)	1h 3m 41s
make (check, macos-14, --with-gmp)	1h 3m 17s
make (test-bundled-gems, macos-14)	53m 54s
make (check, macos-13)	1h 0m 34s
make (check, macos-15)	55m 9s
macOS result	3s
	8h 51m 34s

Provide feedback